The incident at Fishbourne Playing Fields happened between 9pm and 10pm last night.

A 16-year-old boy from Bognor, who knows the victim, has been arrested and is helping West Sussex police with their enquiries. Police are keen to speak to a woman who was walking her dog in the park at the time.

The park has been cordoned off at the back of Salthill Road and police are making door to door enquiries.

Detective Sergeant Russ Burgess, who is investigating the incident, said: ‘We have cordoned the area of the park at the back of Salthill Road and are making house to house enquiries.

‘We are appealing for anyone in the area between 9pm and 10pm and who may have information, to contact police on 101.

‘In particular we are appealing to a woman who was seen walking her dog in the park at that time.

‘The two people involved were known to each other.

‘Neighbourhood officers will be in the village to offer reassurance and answer any questions.’